Ester alcohols, in particular, ester polyols are very useful for the production of polyurethane-based coatings and foams, as well as, polyester applications. The present invention provides a process using renewable resources, such as, oils and fats, fatty acids, and fatty acid esters derived from plants and animals to produce polyurethane foams and lubricants. Further, sources having a carbon-carbon double bond, such as, hydrocarbons, petrochemical, fossil fuel, crude oil and the like may be used in the formation of the ester alkyls. For example, oleochemicals are chemicals that are derived from plants and animal fats. Oleochemicals are analogous to petrochemicals, which are chemicals derived from petroleum. As the price in crude oil increases, there is an increase in demand from oleochemical substances.
Conventionally, ester polyols are produced from animal or vegetable fats using ozonolysis. Organic solvents are used as a solvent in ozonolysis to control the reactivity of the intermediate. The addition of water found in organic solvents suppresses the formation of unwanted byproducts in the intermediates. However, if the ozonolysis is an oxidative process, ketones or carboxylic acids are formed. A disadvantage of this process is that more ozone must be added in the second ozonolysis step to convert the ketones or aldehydes to acids than in the first ozonolysis step.
In a two-stage ozonolysis method of producing polyols from fats or oils, the aldehyde was converted to an acetal, which was then converted by ozone to an ester. PCT Application No. PCT/US2006/016022 (Pub. No. WO2007027223) describes various solvent-based approaches to prepare product ester polyols. One approach involves a two-stage ozonolysis process for the production of product ester polyols where soybean oil is subjected to ozonolysis in the presence of primary polyols, such as, glycerin and a solvent.
In this process, two moles of ozone are required per mole of starting material double bond where the first mole of ozone initially reacts with the double bonds of the starting material to form molozonide intermediates. A molozonide is an unstable cyclic organic compound.
The molozonides dissociate to form carbonyl oxide and aldehyde intermediates. The carbonyl oxide intermediates are trapped with primary polyols, such as, glycerin to produce alkoxy hydroperoxide functionality. The primary polyols also react with the aldehyde functionality produced during the dissociation of the molozonide to produce cyclic acetals and water in an equilibrium process.
A second mole of ozone is then added to convert the cyclic acetals to ester polyols via hydrotrioxides intermediates in a process that occurs at an ambient temperature. The procedure is then completed by heating the reaction mixture, typically by refluxing the solvent, to convert alkoxy hydroperoxides to ester polyols. The main role of the solvent is to provide heat dissipation and cosolubilization of different types of reactants. Most organic solvents have little or no water. However, if water is present, water can react with certain intermediates to form unwanted products.
A variation of the above approach involves the substitution of monoalcohols for primary polyols to form carboxylic esters rather than ester polyols. Carboxylic esters can be converted to ester polyols by transesterification with primary polyols.
However, there still is a need in this technical field for improved methods for the preparation of ester alcohols, particularly with methods that increase the yield of ester alcohols while more efficiently using ozone. Therefore, the present invention seeks to improve the rate of incorporation and delivery of gaseous ozone that is bubbled through the reaction mixture during addition of the second mole of ozone.
The approach and methodology as proposed in the present invention provides a solution with respect to increasing the yield of esters relative to the amount of delivered ozone from a substance having at least one carbon-to-carbon double bond during ozonolysis. The ozonolysis of the double bond forms an aldehyde. An aspect of the present invention includes reacting the aldehyde with a monoalcohol to form an acetal and produce water.
Further, a feature of the present invention includes a refluxing step to remove water formed during the reaction of the aldehyde with the monoalcohol to form an acetal and during reflux from the substance having at least one carbon-to-carbon double bond before performing another ozonolysis reaction. The primary polyols are not subjected to direct oxidation by exposure to ozone because the primary polyols are only used in the subsequent transesterification process. Therefore, the primary polyols are not exposed to ozone.
Another advantage of the present invention is that it uses less expensive feedstock, such as, palm fatty acid distillate (PFAD) and full composition fatty acids that do not require fractionation. PFAD is generally sold for industrial uses and non-food applications. PFAD is a byproduct of palm oil production and potentially viewed as a source of biodiesel. In another aspect of the present invention, sources having a carbon-carbon double bond, such as, hydrocarbons, petrochemical, fossil fuel, crude oil and the like may be used in the formation of the ester alkyls.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate on exemplary technology area where some embodiments described herein may be practiced.